(This is not an EASY question.)

TR1 for Lara and for the most creative and believe-able Virtual Reality of its time! (A lot of other games were still BUSY with general combat games, lots of unreal monsters and LOTs of strange places. But the world of TR brought us almost a real-world that you could almost taste and FEEL, even with its music!)
TR2 technically PUSHED the game into a lot more exploration and abilities.
TR3 gave it another tech nudge, but it was like CORE was testing their market for more modern times and places for their tomb-raiding Lara?
But TR4, with its TRLE Editor, might be considered the real world-shaker, by FAR! (Because almost every country, in the world, contributed to these TR4 adventures from some very small single-level ones to vast mega-level "world class" games that even rivaled CORE's fine work.)
Tomb Raider Anniversary Adult-Material at Yahoo *Make certain that you are 18*
http://groups.yahoo.com/group/TombRaide ... -Material/(Just added links to your TRA site and a few needed things.)
BTW we have artists, like Ranged Weapon and Denadin, who do incredible game-related art!